We begin by describing the unit ball of the free p-convex Banach lattice over a Banach space E (denoted by FBL (p) [E]) as a closed solid convex hull of an appropriate set. Based on it, we show that, if a Banach space E has the λ-Approximation Property, then FBL (p) [E] has the λ-Positive Approximation Property. Further, we show that operators u ∈ B(E, F ) (where E and F are Banach spaces) which extend to lattice homomorphisms from FBL (q) [E] to FBL (p) [F ] are precisely those whose adjoints are (q, p)-mixing. Related results are also obtained for free lattices with an upper p-estimate.